Historically, chiropractic adjusting tables would be used by the chiropractor for his professional lifetime. The tables were made to suit short practitioners and extensions could be rather permanently attached to raise the table in two-inch increments from a twenty inch minimum to a twenty-six inch maximum which generally suited various builds and heights of doctors.
In later years, as practices have grown, a doctor may add additional units and then bring in an associate. If the doctors were not the same height, or did not use the same adjusting technique, a fixed height became a detriment and this problem became amplified in the larger clinics where many doctors were practicing.
In order to alleviate this situation, various arrangements have been proposed to provide chiropractic adjustment tables wherein the height can be varied. Generally, these tables include an elongated table frame upon which are positioned cushioned sections which may slide along the frame to accommodate different-sized persons. They also generally include a foot rest at one end of the frame. The frame itself is arranged to be adjusted in height by an appropriate hydraulic system to raise the entire frame in a vertical direction. In addition, the tables are generally capable of being tilted towards an upright position and the foot rest is utilized as a support for the patient's feet when the table is moved toward the vertical position.
Many of these adjustable height tables are very slow acting or have a very complex means for changing from the inclined or tilting movement to the purely vertical movement of the frame. Some arrangements use a mechanical selector interlock that changes the direction mode but only at a certain cycle termination point so that the mechanism can be engaged or disengaged.
Many of these prior art arrangements have used two hydraulic cylinders for the multi-directional movement. However, these arrangements also require electrical or mechanical trips or interlocks to eliminate any chance of the table traversing two directions at the same time which would expose the patient to the possible danger of the footstep not being in the same position when the patient gets off the table as it was when the patient stepped on it. Such a condition can be particularly disturbing to many patients who have circulatory problems, lack of coordination, impaired vision or other possible maladies.
Some of the adjustable height prior art table arrangements have employed a single hydraulic cylinder to accomplish both tilting of the patient table for loading and unloading the patient and elevation of the table when in a horizontal position to a suitable hight for the chiropractor. However, these arrangements employ various mechanical cam or ramp actuated latches which come into action or release throughout the hydraulic cylinder motion. These arrangements appear difficult to adjust originally and virtually impossible to service in the field should a malfunction occur. Also, the motor and pump units and hydraulic cylinders on such single cylinder arrangements are virtually buried in the equipment thus severely limiting even simple repairs or adjustments.
In all of these adjustable height chiropractic table arrangements, the problem has been to provide a mechanism by means of which the adjusting table can be raised in height in order to suit the needs of the particular doctor while at the same time providing a solid, stable support for the table in its elevated position which will promote a secure feeling for the patient and will permit the doctor to make appropriate adjustments to the patient without having to compensate for side sway or a soft rubbery feel of the patient table when supported in its elevated position. Certain adjustable height arrangements have supported the table in its elevated position by means of a single center post. However, such arrangements do not provide a stable support for the elevated table when adjustments to the neck or other extremities are made by the doctor.
While another prior art arrangement has supported the elevated table at the four corners thereof, the linkage employed to elevate the table to an adjustable height is supported on rollers which provide an insecure, rubbery supporting structure which does not promote a secure feeling on the part of the patient or permit the doctor to be sensitive to the patient's condition. Furthermore, the linkage arrangements of such a structure are subject to side sway, particularly when the joints of the linkage begin to wear. Furthermore, in such prior art arrangement, the linkages used to raise and lower the table are all exposed so that many potentially harmful pinch points are accessible to both the doctor and the patient with the attendant possibility of personal injury thereto.